Layered Double Hydroxides and the Environment: An Overview - Advanced Materials for Agriculture, Food and Environmental Safety - page 16

L-Tyrosine [100]. Choi et al. have made signii cant investigations on the tox-
icity of LDH nanoparticles in vitro and in vivo in applications [97]. Xu et al .
[101] recently reported an ei cient LDH-based delivery for siRNA.
1.6.4 IndustrialApplications
Layered double hydroxides have a large anion exchange capacity, making
them useful for entrapping pesticides, surfactants, nitrates, chromates, etc.,
for the treatment of industrial and environmental wastewater.
As has already been pointed out, LDHs are used as catalysts. h eir appli-
cations are increasing in the industrial production of organic materials and
in conversion of natural gas. h ey also i nd applications in photochemi-
cal reactions. Many authors [102-108] also examined other applications of
LDH materials. Some of these applications include the use of hydrotalcite-
like compounds as additives in photochemistry, electrochemistry and in
functional polymer materials. h ey have other applications in the pharma-
ceutical and biochemical industries [102].
1.6.5 EnvironmentalApplications
In the i eld of environmental technology, much attention has been paid to the
potential applications of synthetic materials as sorbents for organic and inor-
ganic pollutants in water. Layered double hydroxides (LDHs) are used for the
decontamination of the environment and prevent the dispersion of pollut-
ants in nature. A wide range of contaminants can be removed from industrial
el uents or wastewater by anion exchange, adsorption process and catalytic
remediation, using LDHs. Recently, many other molecules such as pesticides,
toxic organic chemicals, greenhouse gases, heavy metals and some other
undesirable inorganic substances have increasingly been targeted for remedi-
ation by using LDHs for the protection of earth, health and the environment.
h ere has been a thorough reinvestigation of LDHs for anion exchange
properties due to recent interest in developing the use of anionic clays for
environmental remediation. h e main characteristics have been studied to
clearly characterize the adsorption properties of the materials under vigor-
ous solid/liquid interface conditions. h e ef ect of sorbent composition,
surface and bulk adsorption, and concentration of adsorption site have
been assessed. h e adsorption capacity is deeply af ected by the nature of
the counteranion of the LDH layer.
In 1983, Miyata [109] i rst reported the ion exchange isotherm of a
series of LDHs leading to the ion selectivity of layered double hydroxides
for monovalent and divalent anions, OH - > F - > Cl - > Br - > NO 3 - > I - and